In conventional bulldozers for instance, a power train composed of an engine, transmission and others is provided in a main frame having an undercarriage, and an operator's cab for a work vehicle (hereinafter referred to as “operator's cab”) is mounted over the power train.
The operator's cab has a floor frame that constitutes the framework of the base part of the operator's cab and a cab frame that is mounted on the floor frame to constitute the framework of the main body part of the operator's cab.
The floor part of the floor frame of the operator's cab is provided with an opening used for maintenance of the power train located thereunder. This opening for maintenance is usually closed up by a lid body attached to the floor frame. During maintenance of the power train, the lid body is removed from the floor frame so that the power train becomes accessible through the opening for maintenance which has been exposed.
In one known structure such as disclosed in Patent Literature 1, the floor part of the floor frame and the lid body used for closing the opening for maintenance defined in the floor part are both of a hollow box-like structure so that the noise made by the power train located under the floor frame can be suppressed.